Photographic elements which produce viewable images consisting essentially of dye, hereinafter also referred to as dye image-generating photographic elements, and which contain both colloidal silver and hydroquinone antistain agent are well known in the photographic art. Such photographic elements can be illustrated by silver halide photographic elements containing a colloidal silver layer. Yellow colloidal silver, also referred to as Carey Lea silver or CLS, is employed in silver halide photographic elements to protect minus blue--i.e., green and/or red sensitized silver halide emulsion layers--from exposure to blue light. Grey colloidal silver is sometimes employed to reduce halation. Colloidal silver is also sometimes used in interlayers to control interimage effects. Hydroquinone antistain agents are commonly used in and/or between silver halide emulsion layers to reduce migration of oxidized developing agent between layers of the photographic element.
To provide a specific illustration, in photographic elements intended to generate multicolor dye images it is conventional practice to coat on a support three separate superimposed dye image-generating layer units, each including at least one silver halide emulsion layer. Within one dye image-generating layer unit is located a blue sensitive silver halide emulsion, usually in combination with at least one compound capable of generating a yellow dye image, typically a yellow dye-forming coupler. Within another dye image-generating layer unit is located a blue sensitive silver halide emulsion which is spectrally sensitized to the green portion of the spectrum, usually also containing at least one compound capable of generating a magenta dye image, typically a magenta dye-forming coupler. Within a third dye image-generating layer unit is located a blue sensitive silver halide emulsion which is spectrally sensitized to the red portion of the spectrum, usually also containing a compound capable of generating a cyan dye image, typically a cyan dye-forming coupler. In each layer unit the image dye generating compound can be located in the emulsion layer or in an adjacent, usually contiguous layer. To protect the green and red sensitized silver halide emulsions from exposure to blue light it is common practice to coat a yellow colloidal silver layer to lie between the dye image-generating layer units containing these emulsions and the source of exposing radiation. Image dye is typically generated as a direct or inverse function of imagewise exposure of silver halide during photographic development. Reaction of developing agent with the silver halide grains during development produces oxidized developing agent which then reacts with the compound capable of generating the dye image, typically "coupling" with the dye-forming coupler to form a dye.
If in this circumstance oxidized developing agent migrates to an adjacent dye image-generating layer unit before reacting with an image dye generating compound, a false record of exposure is produced, sometimes referred to as dye stain. To avoid this, it is common practice to incorporate in an interlayer between silver halide emulsion layers of adjacent color-generating layer units and/or directly in the emulsion and/or other layers of the color-generating layer units a hydroquinone suitably ballasted to restrict its mobility, such hydroquinones being commonly referred to as antistain agents. Silver produced during development is an unwanted by-product which is removed together with colloidal silver by bleaching after the dye image is formed. Thus the photographic elements produce multicolor images which consist essentially of image dye.
A problem that has been observed occasionally in color photographic elements is the formation of random fog spots.